China has successfully grown rice at Tiangong space station
   Since humans sent the first satellite（衛(wèi)星）to space in the 1950s，scientists have been studying an important topic：how to grow food in space if humans will one day live there.A recent experiment（實驗）at the Tiangong space station makes a big step forward.
   Chinese astronauts have successfully grown rice seedlings（幼苗）during the Shenzhou XIV mission. "The rice seedlings are growing very well，" said Zheng Huiqiong，the seedlings of the tall shoot rice variety have reached a height of 30 centimeters.The seedlings of the dwarf rice variety（矮稈水稻品種）have grown to 5 centimeters.
   While there have been other rice experiments in space，this one is the first of its kind to produce the complete life cycle of a plant —it begins with a seed and ends with a mature（成熟的）plant producing new seeds.
   Such food-growing experiments are not just for astronauts.They can also solve food problems on Earth.By sending seeds to space，we can create mutated（突變的）seeds，thanks to microgravity（微重力），lack of air and cosmic rays（宇宙射線）.The seeds can then produce higher yields（產量）on earth.
   For more than 30 years，China has developed over 260 new types of seeds in space.They are planted every year in fields that cover tens of millions of hectares（公頃）.
   According to Yao Tong，an engineer from Hainan Aerospace Engineering Breeding Research Center，30 percent of strawberries sold in Beijing are "space strawberries"，and "space bananas" with a growth cycle shortened from 13 months to 9 months.
（1）When was the first satellite sent to space？ （no more than three words）

In the 1950s.

In the 1950s.

（2）What experiment have the Chinese astronauts successfully done at Tiangong Space Station？ （no more than two words）

Rice seedings.

Rice seedings.

（3）What causes the seeds to mutate？ （no more than seven words）

Microgravity ，lack of air and cosmic rays.

Microgravity ，lack of air and cosmic rays.

（4）How many new kinds of seeds has China developed in space？ （no more than two words）

Over 260.

Over 260.

（5）What is Yao Tong？ （no more than two words）

An engineer.

An engineer.